1. Field of the Invention
The present invention relates to a sintered magnet, especially a rare earth sintered magnet, and to a rotating machine equipped with the same.
2. Description of Related Art
Conventional rare earth sintered magnets containing fluoride compounds or oxyfluoride compounds are disclosed in Patent Literatures 1 to 6 below. In the conventional technology, the fluoride compound used for processing is in the form of powdery or a mixture of powder of the compound and a solvent, and it is difficult to efficiently form a phase containing fluorine along surfaces of magnetic particles. In the above-mentioned conventional method, the fluoride compound or oxyfluoride compound used for the processing is in point contact with the surface of the magnetic particles, and it is difficult for the phase containing fluorine to come in surface contact with the magnetic particles. Therefore, there have been required a relatively large amount of the processing material and heat treatment at high temperatures according to the conventional method.
Non-Patent Literature 1 discloses a magnet that includes a micro sintered magnet coated on the surface thereof with micro particles (1 to 5 μm) of DyF3 or TbF3. It is described in the above-mentioned literature that Dy and F are absorbed by the sintered magnet to form NdOF and Nd oxide.
[Patent Literature 1] JP-A-2003-282312
[Patent Literature 2] JP-A-2006-303436
[Patent Literature 3] JP-A-2006-303435
[Patent Literature 4] JP-A-2006-303434
[Patent Literature 5] JP-A-2006-303433
[Patent Literature 6] JP-A-2008-061333
[Non-Patent Literature 1] IEEE TRANSACTIONS ON MAGNETICS and VOL. 41 No. 10 (2005) Page 3844